This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This project is designed to act as a holding and resource project for animals that have been infected with SIVor HIV that are no longer required on the original project. The animals will be maintained in BSL-2/3 facilities, either in the I- Wing or at the PFS. They will be monitored clinically to help define the natural pathogenesis of the disease. No research will be done on this project;however, the animals may be reassigned to other projects to serve as subjects in experimental drug evaluations, pathogenesis studies, vaccine studies, or studies requiring immunosuppressed and/or SIV/HIV-viremic animals. Blood will be drawn every 2-3 months for viral isolation, serology, CBC, serum chemistry, and T- cell subset analysis. In the event that an animal should become unresponsive to treatment or should die, a complete necropsy will be performed using the standard SIV/HIV pathology protocol.